Wind turbines of varying output are already firmly established as one of a number of means for generating power. Developments in recent years have made these wind power units even larger and more efficient.
The area swept by the rotor of the wind power unit can be seen as the area from which energy can be taken from the wind. In practice it is disadvantageous for the various components of the wind power unit, such as the mast, the gondola and the spinner or the shaft of the wind power unit to disturb the air flow within this area. This causes eddies, turbulence and lees, which result in a reduction in the area swept by the rotor and thus a lower energy yield.
It is also disadvantageous if the wind power units behind in the wind direction are negatively affected by the turbulence generated. Because an at least partly disturbed, turbulent air flow acts on these wind power plants, their efficiency is diminished.
A further disadvantage is that the individual rotor blades are exposed to the force or pressure of the air flow, which results in a bending load. As a rotor blade sweeps past the mast of the wind power unit, the load on the rotor blade is relieved for a brief period. There is thus a periodic load change, which is expressed in the form of unwanted vibration. These dynamic effects are propagated over the rotor blade hub, the generator, bearings, shafts, drives, transmission to the mast, so that all the components have to have larger dimensions to ensure the required endurance strength. These precautions mean that the wind power unit costs more.
It is already known from WO 97/04280 that the boundary layer of elements around which there is a flow can be influenced by means of a structured surface but electric or magnetic fields are required for this.